Refrigeration Apparatus

ABSTRACT

A refrigeration apparatus, provided with a refrigerant circuit ( 90 ) having a plurality of refrigerant circulating routes and capable of operation in a mode where the plurality of refrigerant circulating routes differ in refrigerant evaporation temperature and/or in refrigerant condensation temperature, is activated by a single scroll compressor ( 10 ) including a casing ( 11 ) in which are arranged two compression mechanisms ( 31, 32 ), thereby making it possible to accomplish install-space savings, cost-cutting, and high-efficiency operation.

TECHNICAL FIELD

The present invention relates to refrigeration apparatuses and morespecifically to a refrigeration apparatus provided with a refrigerantcircuit having a plurality of refrigerant circulating routes and capableof operation in a mode where the plurality of refrigerant circulatingroutes differ in refrigerant evaporation temperature and/or refrigerantcondensation temperature.

BACKGROUND ART

Refrigeration apparatuses which perform refrigeration cycles are knownin the prior art. Such a type of refrigeration apparatus has been usedwidely as an air conditioner for providing room cooling/heating and acooling machine such as a refrigerator, freezer or showcase for thestorage of foods. Some refrigeration apparatuses provide both roomcooling and refrigerator's storage space cooling (for example, seeJapanese Patent Application Kokai Publication No. 2002-349980). Thistype of refrigeration apparatus is generally installed in conveniencestores.

With reference to FIG. 11 showing a refrigerant circuit (100) of theabove-described refrigeration apparatus, discharge pipes of twocompressors (101, 102) join and their junction is linked to a singlehigh-pressure gas pipe (103). The high-pressure gas pipe (103) is linkedto one end of an outdoor heat exchanger (104). The other end of theoutdoor heat exchanger (104) is branch-connected, through a liquid pipe(107), to one end of an air-conditioning heat exchanger (105) for roomair-conditioning and to one end of a cooling heat exchanger (106) forrefrigerator's storage space cooling. Branch pipes (108, 109) of theliquid pipe are provided with expansion valves (110, 111), respectively.And, the other end of the air-conditioning heat exchanger (105) isconnected, through a first low-pressure gas pipe (112), to the suctionside of the first compressor (101). The other end of the cooling heatexchanger (106) is connected, through a second low-pressure gas pile(113), to the suction side of the second compressor (102). By virtue ofthe above-described arrangement, the temperature at which refrigerantevaporates in the air-conditioning heat exchanger (105) differs from thetemperature at which refrigerant evaporates in the cooling heatexchanger (106).

Problems that Invention Intends to Solve

In the above-described conventional refrigeration apparatus, however,each refrigerant circulating route requires a respective compressor, inother words the provision of the compressors (101, 102) is required.Consequently, the installation of the compressors (101, 102) requires alarge space. Another problem is that the provision of the twocompressors (101, 102) increases costs in comparison with the provisionof a single compressor.

With the above-described problems in mind, the present invention wasmade. Accordingly, an object of the present invention is to accomplishinstallation space reduction and cost reduction by enabling a singlecompressor to activate a refrigeration apparatus provided with arefrigerant circuit having a plurality of refrigerant circulating routesand capable of operation in a mode where the plurality of refrigerantcirculating routes differ in refrigerant evaporation temperature and/orrefrigerant condensation temperature.

DISCLOSURE OF INVENTION

In the present invention, a compressor with two compression mechanisms(31, 32) contained in a single casing (11) is used in a refrigerantcircuit (90) having a plurality of refrigerant circulating routes.

More specifically, the present invention is directed to a refrigerationapparatus provided with a refrigerant circuit (90) having a plurality ofrefrigerant circulating routes and capable of operation in a mode wherethe plurality of refrigerant circulating routes differ in at least oneof refrigerant evaporation temperature and refrigerant condensationtemperature.

A first invention is characterized in that a compressor (10) of therefrigerant circuit (90) comprises a single casing (11) in which a firstcompression mechanism (31) linked to a first refrigerant circulatingroute and a second compression mechanism (32) linked to a secondrefrigerant circulating route are arranged.

In the first invention, refrigerant discharged from the firstcompression mechanism (31) circulates through the first refrigerantcirculating route of the refrigerant circuit (90) while, on the otherhand, refrigerant discharged from the second compression mechanism (32)circulates through the second refrigerant circulating route of therefrigerant circuit (90).

The second invention is characterized in that in the refrigerationapparatus of the first invention the first and second compressionmechanisms (31, 32) differ from each other in compression ratio.

In the second invention, refrigerant discharged from the firstcompression mechanism (31) circulates through the first refrigerantcirculating route of the refrigerant circuit (90) while, on the otherhand, refrigerant discharged from the second compression mechanism (32)circulates through the second refrigerant circulating route of therefrigerant circuit (90). Since the first compression mechanism (31) andthe second compression mechanism (32) differ from each other incompression ratio, this makes it possible to provide to each refrigerantcirculating route a supply of refrigerant at a respective suitablepressure.

A third invention is characterized in that in the refrigerationapparatus of the first invention the first and second compressionmechanisms (31, 32) differ from each other in displacement volume.

In the third invention, refrigerant discharged from the firstcompression mechanism (31) circulates through the first refrigerantcirculating route of the refrigerant circuit (90) while, on the otherhand, refrigerant discharged from the second compression mechanism (32)circulates through the second refrigerant circulating route of therefrigerant circuit (90). Since the first compression mechanism (31) andthe second compression mechanism (32) differ from each other indisplacement volume, this makes it possible to provide to eachrefrigerant circulating route a supply of refrigerant at a respectivesuitable circulation amount.

A fourth invention is characterized in that in the refrigerationapparatus of any one of the first to third inventions the first andsecond compression mechanisms (31, 32) are scroll compressionmechanisms; an orbiting scroll (50) integrated by sequentially layeringa first flat-plate part (51), a first movable-side wrap (53), a secondflat-plate part (52) and a second movable-side wrap (54), and a fixedscroll (40) having a first stationary-side wrap (42) which engages thefirst movable-side wrap (53) and a second stationary-side wrap (47)which engages the second movable-side wrap (54) are provided; the firststationary-side wrap (42) and the first movable-side wrap (53) togetherform the first compression mechanism (31); and the secondstationary-side wrap (47) and the second movable-side wrap (54) togetherform the second compression mechanism (32).

In the fourth invention, the refrigerant circuit (90), having the tworefrigerant circulating routes and capable of operation in a mode wherethe two refrigerant circulating routes differ in refrigerant evaporationtemperature and/or refrigerant condensation temperature, is activated bythe single compressor formed by the two-tiered compression mechanisms(31, 32) wherein the first compression mechanism (31) comprises thefirst stationary-side wrap (42) and the first movable-side wrap (53)while, on the other hand, the second compression mechanism (32)comprises the second stationary-side wrap (47) and the secondmovable-side wrap (54).

A fifth invention is characterized in that in the refrigerationapparatus of any one of the first to third inventions the first andsecond compression mechanisms (31, 32) are scroll compressionmechanisms; an orbiting scroll (50) having a first movable-side wrap(53) formed in standing manner on one surface of a flat-plate part (55)and a second movable-side wrap (54) formed in standing manner on theother surface of the flat-plate part (55), and a fixed scroll (40)having a first stationary-side wrap (42) which engages the firstmovable-side wrap (53) and a second stationary-side wrap (47) whichengages the second movable-side wrap (54) are provided; the firststationary-side wrap (42) and the first movable-side wrap (53) togetherform the first compression mechanism (31); and the secondstationary-side wrap (47) and the second movable-side wrap (54) togetherform the second compression mechanism (32).

In the fifth invention, the refrigerant circuit (90), having the tworefrigerant circulating routes and capable of operation in a mode wherethe two refrigerant circulating routes differ in refrigerant evaporationtemperature and/or refrigerant condensation temperature, is activated bythe single compressor having the first compression mechanism (31) andthe second compression mechanism (32) which are disposed opposite toeach other with the flat-plate part (55) of the orbiting scroll (50)lying therebetween.

Effects

In accordance with the first invention, the scroll compressor (10) ofthe refrigerant circuit (90) has, in the single casing (11), the firstcompression mechanism (31) linked to the first refrigerant circulatingroute and the second compression mechanism (32) linked to the secondrefrigerant circulating route. In other words, the provision of a singlecompressor (i.e., the scroll compressor (10)) makes it possible toaccomplish install-space savings and apparatus cost reduction.

If each refrigerant circulating route is provided with a respectivecompressor, this increases the number of points requiring welding andbrazing. Consequently, refrigerant leakage due to aged deterioration andvibrations of the apparatus may occur, thereby making the apparatus lessefficient and producing factors causing global warming. The presentinvention makes these problems avoidable because it employs only onecompressor (i.e., the scroll compressor (10)).

In accordance with the second invention, the first compression mechanism(31) and the second compression mechanism (32) differ from each other incompression ratio, thereby making it possible to perform, at the ratioof the condensation pressure and the evaporation pressure of eachrefrigerant circulating route (i.e., at the pressure ratio), efficientcompression without losses such as over-compression and compressioninsufficiency in the refrigerant circuit (90).

In accordance with the third invention, the first compression mechanism(31) and the second compression mechanism (32) differ from each other indisplacement volume, thereby making it possible to provide to eachrefrigerant circulating route of the refrigerant circuit (90) a supplyof refrigerant at a respective suitable circulation amount.

In accordance with the fourth invention, it employs a compressor formedby the two-tiered compression mechanisms (31, 32) of the scroll type,thereby making it possible to achieve considerable downsizing of theapparatus. Furthermore, it is possible to form the first compressionmechanism (31) and the second compression mechanism (32) by using twostationary-side wraps and two movable-side wraps of a conventionalscroll compressor provided with a single compression mechanism. Thismakes it possible to achieve a share of component parts with theconventional scroll compressor, thereby achieving cost-cutting.

In accordance with the fifth invention, it employs the orbiting scroll(50) having the first movable-side wrap (53) formed in a standing manneron one surface of the flat-plate part (55) and the second movable-sidewrap (54) formed in a standing manner on the other surface of theflat-plate part (55), thereby making it possible to reduce the number ofcomponent parts and to achieve cost-cutting.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross sectional view showing the arrangement of ascroll compressor in a first embodiment of the present invention;

FIG. 2 is an enlarged cross sectional view showing the main part of thescroll compressor of FIG. 1;

FIG. 3 is a cross sectional view showing a first stationary-side memberof a fixed scroll;

FIG. 4 is a cross sectional view showing an orbiting scroll;

FIG. 5 is a top plan view showing the first stationary-side member andthe orbiting scroll;

FIG. 6 is a diagram showing the arrangement of a refrigerant circuitemploying the scroll compressor of FIG. 1;

FIG. 7 is a diagram showing the arrangement of a refrigerant circuit ofa second embodiment of the present invention;

FIG. 8 is a diagram showing the arrangement of a refrigerant circuitaccording to a first variation of the second embodiment;

FIG. 9 is a diagram showing the arrangement of a refrigerant circuitaccording to a second variation of the second embodiment;

FIG. 10 is a partial cross sectional view of a scroll compressor of athird embodiment of the present invention; and

FIG. 11 is a refrigerant circuit diagram of a conventional refrigerationapparatus.

BEST MODE FOR CARRYING OUT INVENTION

Hereinafter, preferred embodiments of the present invention aredescribed with reference to the drawings. Each of the followingembodiments relates to a refrigeration apparatus provided with arefrigerant circuit whose compression mechanism is formed by a scrollcompressor.

First Embodiment of Invention

A first embodiment of the present invention is now described, startingwith its scroll compressor.

As shown in FIG. 1, the scroll compressor (10) has a casing (11) shapedlike an oblong, cylindrical, hermetically-sealed container. Sequentiallyarranged from top to bottom in the inside of the casing (11) are a mainmechanism (30), an electric motor (16), and a lower bearing (19). Inaddition, a drive shaft (20) vertically extending in the inside of thecasing (11) is mounted as a rotating shaft.

The inside of the casing (11) is separated into up and down by a housing(33) of the main mechanism (30). More specifically, in the inside of thecasing (11), the space defined above the housing (33) serves as alow-pressure chamber (12) while, on the other hand, the space definedbelow the housing (33) serves as a high-pressure chamber (13).

The high-pressure chamber (13) contains the electric motor (16) and thelower bearing (19). The electric motor (16) has a stator (17) and arotor (18). The stator (17) is firmly attached to a part of the mainbody of the casing (11). On the other hand, the rotator (18) is firmlyattached to a vertically central part of the drive shaft (20). The lowerbearing (19) is firmly attached to a part of the main body of the casing(11). The lower bearing (19) rotatably supports the lower end of thedrive shaft (20).

The casing (11) has a tube-like discharge port (74) which is a firstdischarge port. One end of the first discharge port (74) opens to aspace at a level above the electric motor (16) in the high-pressurechamber (13).

A main bearing (34) is formed in the housing (33) of the main mechanism(30), such that it vertically passes through the housing (33). The driveshaft (20) is inserted through the main bearing (34). The drive shaft(20) is rotatably supported by the main bearing (34). An upper endportion of the drive shaft (20) projecting above the level of thehousing (33) forms an eccentric part (21). The eccentric part (21) iseccentric relative to the central axis of the drive shaft (20).

Attached to a part of the drive shaft (20) situated between the housing(33) and the stator (17) is a balance weight (25). An oil feeding path(not shown) is formed in the drive shaft (20). Refrigeration oilcollected on the bottom of the housing (33) is pumped up from the lowerend of the drive shaft (20) by action of an oil feeding pump disposed atthe lower end of the drive shaft (20). Then, the pumped-up refrigerationoil is supplied, through the oil feeding path, to each section.Furthermore, a discharge path (22) is formed in the drive shaft (20).The discharge path (22) will be described later.

As shown in FIG. 2, the low-pressure chamber (12) contains stationaryand orbiting scrolls (40, 50) of the main mechanism (30). In the mainmechanism (30), a first compression mechanism (31) and a secondcompression mechanism (32) are formed. The low-pressure chamber (12)further contains an Oldham ring (39).

The fixed scroll (40) is made up of a first stationary-side member (41)and a second stationary-side member (46). The first and secondstationary-side members (41, 46) together forming the fixed scroll (40)are firmly attached to the housing (33).

As also shown in FIG. 3, the first stationary-side member (41) has afirst stationary-side wrap (42) and a first outer peripheral part (43).FIG. 3 is an illustration showing only the first stationary-side member(41) in a cross section taken along the line A-A of FIG. 2.

The first stationary-side wrap (42) is shaped like a spiral wall theheight of which is constant. On the other hand, the first outerperipheral part (43) is shaped like a thick ring encompassing the firststationary-side wrap (42). The first outer peripheral part (43) isformed integrally with the first stationary-side wrap (42). In otherwords, in the first stationary-side member (41), the firststationary-side wrap (42) projects from the inner peripheral surface ofthe first outer peripheral part (43). In addition, three insertion holes(44) and three bolt holes (45) are formed through the first outerperipheral part (43). The first stationary-side member (41) is firmlyfastened, by bolts slid into the bolt holes (45), to the housing (33).

One end of a tube-like suction port (73) which is a first suction portis inserted into the first stationary-side member (41) (see FIG. 2). Thefirst suction port (73) is provided, such that it passes through anupper end portion of the casing (11). A suction check valve (35) ismounted at the bottom of the first suction port (73) in the firststationary-side member (41). The suction check valve (35) is made up ofa valve body (36) and a coil spring (37). The valve body (36) is shapedlike a cap. The valve body (36) is disposed, such that it closes thelower end of the first suction port (73). In addition, the valve body(36) is pressed against the lower end of the first suction port (73) bythe coil spring (37).

As shown in FIG. 2, the second stationary-side member (46) has a secondstationary-side wrap (47), a second outer peripheral part (48), and athird flat-plate part (49). The second stationary-side member (46), whenviewed as a whole, is shaped like a disc smaller in diameter andthickness than the first stationary-side member (41). The thirdflat-plate part (49) is shaped like a disc and is disposed at the upperside of the second stationary-side member (46). The second outerperipheral part (48) is formed integrally with the third flat-plate part(49) and extends downwardly from the third flat-plate part (49). Thesecond outer peripheral part (48) is shaped like a thick ring having thesame outer diameter as that of the third flat-plate part (49).

In the second stationary-side member (46), the second stationary-sidewrap (47) is disposed inside the second outer peripheral part (48). Thesecond stationary-side wrap (47) is formed integrally with the thirdflat-plate part (49). The second stationary-side wrap (47) is shapedlike a spiral wall the height of which is shorter than that of the firststationary-side wrap (42). The second stationary-side wrap (47) extendsdownwardly from the lower surface of the third flat-plate part (49). Inaddition, the spiral direction of the second stationary-side wrap (47)is the same as that of the first stationary-side wrap (42). Statedanother way, both the first stationary-side wrap (42) and the secondstationary-side wrap (47) are shaped like a right-handed spiral wall(see FIG. 3).

One end of a tube-like suction port (76) which is a second suction portis inserted into the second stationary-side member (46). The secondsuction port (76) is formed, such that it passes through an upper endpart of the casing (11). In addition, centrally formed in the thirdflat-plate part (49) of the second stationary-side member (46) is adischarge opening (66) which is a second discharge opening. The seconddischarge opening (66) is formed, such that it passes through the thirdflat-plate part (49). One end of a tube-like discharge port (75) whichis a second discharge port is inserted into the second discharge opening(66). The second discharge port (75) is formed, such that it passesthrough an upper end part of the casing (11).

The orbiting scroll (50) has a first flat-plate part (51), a firstmovable-side wrap (53), a second flat-plate part (52), a secondmovable-side wrap (54), and support rod members (61) by which the firstflat-plate part (51), the first movable-side wrap (53), the secondflat-plate part (52), and the second movable-side wrap (54) aresequentially integrally layered one upon the other. The firstmovable-side wrap (53) is formed integrally with the first flat-platepart (51). On the other hand, the second movable-side wrap (54) isformed integrally with the second flat-plate part (52). In the orbitingscroll (50), the three support rod members (61) are mounted, in astanding manner, on the upper surface of the first flat-plate part (51)formed integrally with the first movable-side wrap (53), and the secondflat-plate part (52) formed integrally with the second movable-side wrap(54) is placed on the support rod members (61). And, in the orbitingscroll (50), the first flat-plate part (51), the support rod members(61), and the second flat-plate part (52) which are placed one upon theother are fastened together by bolts (62).

The first flat-plate part (51) and the first movable-side wrap (53) aredescribed by making reference to FIGS. 2, 4, and 5. FIG. 4 is anillustration showing only the orbiting scroll (50) in a cross sectiontaken along the line A-A of FIG. 2. And, FIG. 5 is an illustrationshowing the first stationary-side member (41) and the orbiting scroll(50) in a cross section taken along the line A-A of FIG. 2.

As shown in FIG. 4, the first flat-plate part (51) is shaped like agenerally circular flat-plate. The front surface (upper surface in FIG.2) of the first flat-plate part (51) is in sliding contact with thelower end surface of the first stationary-side wrap (42). The firstflat-plate part (51) has three radially projecting projections. Thethree support rod members (61) are mounted, in a standing manner, on thethree projections, respectively. Each support rod member (61) is asomewhat thick, tube-like member and is formed as a separate body fromthe first flat-plate part (51).

The first movable-side wrap (53) is shaped like a spiral wall the heightof which is constant. The first movable-side wrap (53) is mounted, in astanding manner, on the front surface side (upper surface side in FIG.2) of the first flat surface part. The first movable-side wrap (53)engages the first stationary-side wrap (42) of the first stationary-sidemember (41) (see FIG. 5). And, the side surface of the firstmovable-side wrap (53) is in sliding contact with the side surface ofthe first stationary-side wrap (42).

As shown in FIG. 2, the second flat-plate part (52) is shaped like aflat plate approximately identical in shape with the first flat-platepart (51). The rear surface (lower surface in FIG. 2) of the secondflat-plate part (52) is in sliding contact with the upper end surface ofthe first stationary-side wrap (42) while, on the other hand, the frontsurface (upper surface in FIG. 2) thereof is in sliding contact with thelower end surface of the second stationary-side wrap (47).

The second movable-side wrap (54) is mounted, in a standing manner, onthe front surface side (upper surface side in FIG. 2) of the secondflat-plate part (52). The spiral direction of the second movable-sidewrap (54) is the same as the spiral direction of the first movable-sidewrap (53). In other words, the first movable-side wrap (53) and thesecond movable-side wrap (54) are each shaped like a right-handed spiralwall (see FIG. 4).

In the main mechanism (30), the first stationary-side wrap (42), thefirst movable-side wrap (53), the first flat-plate part (51), and thesecond flat-plate part (52) together form a first compression chamber(71). And, the first flat-plate part (51), the second flat-plate part(52) and the first movable-side wrap (53) in the orbiting scroll (50),and the first stationary-side member (41) in the fixed scroll (40)having the first stationary-side wrap (42) together form the firstcompression mechanism (31).

In addition, in the main mechanism (30), the second stationary-side wrap(47), the second movable-side wrap (54), the second flat-plate part(52), and the third flat-plate part (49) together form a secondcompression chamber (72). And, the second flat-plate part (52) and thesecond movable-side wrap (54) in the orbiting scroll (50), and thesecond stationary-side member (46) in the fixed scroll (40) having thethird flat-plate part (49) and the second stationary-side wrap (47)together form the second compression mechanism (32).

Additionally, in the main mechanism (30), the compression ratio in thesecond compression mechanism (32) is higher than the compression ratioin the first compression mechanism (31). In other words, the ratio ofmaximum to minimum volume in the second compression chamber (72) is sethigher than the ratio of maximum to minimum volume in the firstcompression chamber (71). Here, the compression ratio in the secondcompression mechanism (32) is set greater than the compression ratio inthe first compression mechanism (31). Alternatively, the compressionratio in the second compression mechanism (32) may be set smaller thanthe compression ratio in the first compression mechanism (31), or thecompression mechanisms (31, 32) may have the same compression ratio,depending on the use conditions of the scroll compressor (10).

Furthermore, in the main mechanism (30), the displacement volume in thesecond compression mechanism (32) is smaller than the displacementvolume in the first compression mechanism (31). Alternatively, thedisplacement volume in the second compression mechanism (32) may be setgreater than the displacement volume in the first compression mechanism(31), or the compression mechanisms (31, 32) may have the samedisplacement volume, depending on the use conditions of the scrollcompressor (10).

Centrally formed in the first flat-plate part (51) of the orbitingscroll (50) is a discharge opening (63) which is a first dischargeopening. The first discharge opening (63) passes through the firstflat-plate part (51). In addition, a bearing part (64) is formed in thefirst flat-plate part (51). The bearing part (64) is formed into anapproximately cylindrical shape. The bearing part (64) is formed, in aprojecting manner, on the rear surface side (lower surface side in FIG.2) of the first flat-plate part (51). Furthermore, a collar part (65)shaped like a collar is formed at the lower end of the bearing part(64).

A seal ring (38) is mounted between the lower surface of the collar part(65) of the bearing part (64) and the housing (33). A supply ofhigh-pressure refrigeration oil is provided, through the oil feedingpath of the drive shaft (20), to the inside of the seal ring (38). Whenhigh-pressure refrigeration oil is fed to the inside of the seal ring(38), oil pressure acts on the bottom surface of the collar part (65),thereby pushing the orbiting scroll (50) upwardly.

The eccentric part (21) of the drive shaft (20) is inserted into thebearing part (64) of the first flat-plate part (51). The entrance end ofthe discharge path (22) opens at the upper end surface of the eccentricpart (21). The discharge path (22) is formed, such that its portion inthe vicinity of the entrance end is slightly greater in diameter, and atubular seal (23) and a coil spring (24) are mounted in the dischargepath (22). The tubular seal (23) is shaped like a pipe whose insidediameter is slightly greater than the diameter of the first dischargeopening (63). The tubular seal (23) is pressed against the rear surfaceof the first flat-plate part (51) by the coil spring (24). In addition,the exit end of the discharge path (22) opens at a portion of the sidesurface of the drive shaft (20) situated between the stator (17) and thelower bearing (19) (see FIG. 1).

An Oldham ring (39) is inserted between the first flat-plate part (51)and the housing (33). The Oldham ring (39) has a pair of keys whichengage the first flat-plate part (51) and another pair of keys whichengage the housing (33). And, the Oldham ring (39) forms a mechanism forpreventing the orbiting scroll (50) from rotating.

As shown in FIG. 6, the scroll compressor (10) of the present embodimentis disposed in a refrigerant circuit (90) of the refrigerationapparatus. In the refrigerant circuit (90), refrigerant is circulatedand as a result a vapor compression refrigeration cycle is performed.

The refrigerant circuit (90) is provided with two condensers (91, 94)and two expansion valves (92, 95). In the refrigerant circuit (90), therefrigerant condensation temperature in the second condenser (94) is sethigher than the refrigerant condensation temperature in the firstcondenser (91).

In the refrigerant circuit (90), one end of the first condenser (91) islinked to the first discharge port (74) of the scroll compressor (10)and the other end thereof is linked to one end of the first expansionvalve (92). On the other hand, one end of the second condenser (94) islinked to the second discharge port (75) of the scroll compressor (10)and the other end thereof is linked to one end of the second expansionvalve (95). The other ends of the first and second expansion valves (92,95) join and their junction is in connection with one end of anevaporator (93). The other end of the evaporator (93) is divided intobranches one of which is linked to the first suction port (73) of thescroll compressor (10) and the other of which is linked to the secondsuction port (76) of the scroll compressor (10).

Running Operation

In the scroll compressor (10), rotational power generated by theelectric motor (16) is transferred to the orbiting scroll (50) by thedrive shaft (20). The orbiting scroll (50) which engages the eccentricpart (21) of the drive shaft (20) is guided by the Oldham ring (39) andmoves in an orbital path without rotation.

With the orbital motion of the orbiting scroll (50), low-pressurerefrigerant evaporated in the evaporator (93) is drawn into the firstsuction port (73) and the second suction port (76). The low-pressurerefrigerant flows into the first compression chamber (71) and the secondcompression chamber (72). As the first movable-side wrap (53) of theorbiting scroll (50) moves, the volume of the first compression chamber(71) decreases and as a result the refrigerant in the first compressionchamber (71) is compressed while, on the other hand, as the secondmovable-side wrap (54) moves, the volume of the second compressionchamber (72) decreases and as a result the refrigerant in the secondcompression chamber (72) is compressed.

The refrigerant compressed in the first compression chamber (71) flows,through the discharge opening (63), into the discharge path (22).Thereafter, the high-pressure refrigerant leaves the discharge path (22)and flows into the high-pressure chamber (13). Then, the high-pressurerefrigerant passes through the first discharge port (74), and isdischarged out of the casing (11). Meanwhile, the refrigerant compressedin the second compression chamber (72) passes through the seconddischarge port (75), and is discharged out of the casing (11).

In the way as described above, in the scroll compressor (10),refrigerant compressed by the first compression mechanism (31) isdischarged through the first discharge port (74) while on the other handrefrigerant compressed by the second compression mechanism (32) isdischarged through the second discharge port (75). The pressure of therefrigerant discharged through the second discharge port (75) is higherthan the pressure of the refrigerant discharged through the firstdischarge port (74). The refrigerant discharged through the firstdischarge port (74) condenses in the first condenser (91) and thereafteris pressure-reduced by the first expansion valve (92). On the otherhand, the refrigerant discharged through the second discharge port (75)condenses in the second condenser (94) and thereafter ispressure-reduced by the second expansion valve (95).

The refrigerant pressure-reduced by the first expansion valve (92) andthe refrigerant pressure-reduced by the second expansion valve (95) flowinto each other. Thereafter, the merged refrigerant is introduced intothe evaporator (93). In the evaporator (93), the refrigerant evaporates,and thereafter the flow of the refrigerant is divided into two branchflows. One of the two refrigerant branch flows is drawn, through thefirst suction port (73), into the first compression chamber (71) of thefirst compression mechanism (31). On the other hand, the otherrefrigerant branch flow is drawn, through the second suction port (76),into the second compression chamber (72) of the second compressionmechanism (32).

As described above, in accordance with the present embodiment, in therefrigerant circuit (90) provided with the two condensers (91, 94)having different refrigerant condensation temperatures, the refrigerantis compressed by the single scroll compressor (10), thereby making itpossible to provide simplification of the refrigeration apparatusconfiguration.

Effects of First Embodiment

In the refrigeration apparatus of the first embodiment which is providedwith the refrigerant circuit (90) having two refrigerant circulatingroutes (plural refrigerant circulating routes) which differ from eachother in refrigerant condensation temperature, the refrigerant circuit(90) is activated by the single scroll compressor (10) having the twocompression mechanisms (31, 32). And, since the first compressionmechanism (31) and the second compression mechanism (32) differ fromeach other in compression ratio and displacement volume, this makes itpossible to supply each refrigerant circulating route with refrigerantat a respective suitable pressure and at a respective suitablecirculation amount. As a result, it becomes possible for the apparatusto efficiently operate with smaller loss. In addition, since only thesingle scroll compressor (10) is provided, this accomplishesinstall-space savings and the apparatus cost is also cut down.

Furthermore, the first embodiment employs the scroll compressor (10)formed by the two-tiered compression mechanisms (31, 32), and thisscroll compressor (10) is realized by the addition of only the secondflat-plate part (52) provided with the second movable-side wrap (54),the second stationary-side member (46), the second suction port (76) andthe second discharge port (75), to a conventional scroll compressorhaving, as a compression mechanism, only the first compression mechanism(31), i.e., a scroll compressor in which the second flat-plate part (52)is not provided with the second movable-side wrap (54) and neither ofthe second stationary-side member (46), the second suction port (76),and the second discharge port (75) are provided. Accordingly, the shareof component parts with the conventional scroll compressor becomespossible, thereby cutting down the cost.

In addition, even if the compression ratio of either one of the routesis high and as a result the temperature of discharge gas becomes high,heat generated in the upper and lower compression chambers (71, 72) istransferred through the flat-plate part (52) positioned therebetween.This lessens the rise in temperature. Therefore, improvements inapparatus reliability are accomplished.

Second Embodiment of Invention

A second embodiment of the present invention is described. As shown inFIG. 7, the second embodiment differs from the first embodiment inconfiguration of the refrigerant circuit (90). The configuration of thescroll compressor (10) is the same as in the first embodiment.Accordingly, only the configuration of the refrigerant circuit (90) isdescribed below.

The refrigerant circuit (90) of the second embodiment is provided withtwo expansion valves (92, 95) and two evaporators (93, 96). In therefrigerant circuit (90), the temperature at which refrigerantevaporates in the second evaporator (96) is so set as to be lower thanthe temperature at which refrigerant evaporates in the first evaporator(93).

In the refrigerant circuit (90), the first and second discharge ports(74, 75) of the scroll compressor (10) join and their junction is linkedto one end of the condenser (91). The other end of the condenser (91) isdivided into branches one of which is linked to the first expansionvalve (92) and the other of which is linked to the second expansionvalve (95). One end of the first evaporator (93) is linked to the firstexpansion valve (92) while the other end thereof is linked to the firstsuction port (73) of the scroll compressor (10). One end of the secondevaporator (96) is linked to the second expansion valve (95) while theother end thereof is linked to the second suction port (76) of thescroll compressor (10).

In the scroll compressor (10), refrigerant compressed by the firstcompression mechanism (31) is discharged through the first dischargeport (74) while on the other hand refrigerant compressed by the secondcompression mechanism (32) is discharged through the second dischargeport (75). The pressure of the refrigerant discharged through the firstdischarge port (74) and the pressure of the refrigerant dischargedthrough the second discharge port (75) are the same. The refrigerantdischarged through the first discharge port (74) and the refrigerantdischarged through the second discharge port (75) condense in thecondenser (91). After leaving the condenser (91), the flow of thecondensed refrigerant is divided into two branch flows.

One of the two refrigerant branch flows is pressure-reduced by the firstexpansion valve (92), evaporates in the first evaporator (93), and isdrawn, through the first suction port (73), into the first compressionchamber (71) of the first compression mechanism (31). Meanwhile, theother refrigerant branch flow is pressure-reduced in the secondexpansion valve (95), evaporates in the second evaporator (96), and isdrawn, through the second suction port (76), into the second compressionchamber (72) of the second compression mechanism (32). At that time, inthe refrigerant circuit (90), the degree of opening of the secondexpansion valve (95) is set smaller than that of the first expansionvalve (92), and the refrigerant evaporation pressure in the secondevaporator (96) is set lower than that in the first evaporator (93).

In the refrigeration apparatus of the second embodiment provided withthe refrigerant circuit (90) having two refrigerant circulating routes(plural refrigerant circulating routes) which differ from each other inrefrigerant evaporation temperature, the refrigerant circuit (90) isactivated by the single scroll compressor (10) having the twocompression mechanisms (31, 32). And, since the first compressionmechanism (31) and the second compression mechanism (32) differ incompression ratio and displacement volume, this makes it possible tosupply each refrigerant circulating route with refrigerant at arespective suitable pressure and at a respective suitable circulationamount. As a result, it becomes possible for the apparatus toefficiently operate with smaller loss. In addition, since only thesingle scroll compressor (10) is provided, this accomplishesinstall-space savings and the apparatus cost is also cut down.

Variation of Second Embodiment

In the second embodiment, the refrigerant circuit (90) may be arrangedas shown in FIG. 8.

The refrigerant circuit (90) of the present variation is also providedwith two expansion valves (92, 95) and two evaporators (93, 96). Inaddition, like the example of FIG. 7, the refrigerant evaporationtemperature in the second evaporator (96) is set lower than that in thefirst evaporator (93).

In the present variation, the first discharge port (74) of the scrollcompressor (10) is linked to one end of the condenser (91). The otherend of the condenser (91) is divided into two branches one of which islinked to the first expansion valve (92) and the other of which islinked to the second expansion valve (95). One end of the firstevaporator (93) is linked to the first expansion valve (92) while theother end thereof is linked to the first suction port (73) of the scrollcompressor (10). One end of the second evaporator (96) is linked to thesecond expansion valve (95) while the other end thereof is linked to thesecond suction port (76) of the scroll compressor (10). In addition, thesecond discharge port (75) of the scroll compressor (10) is linked to asuction pipe extending between the first evaporator (93) and the firstsuction port (73).

In the present variation, for example 90% of the total amount ofrefrigerant circulation in the refrigerant circuit (90) flows throughthe first evaporator (93) and the rest (10%) flows through the secondevaporator (96).

In the scroll compressor (10), refrigerant compressed by the firstcompression mechanism (31) is discharged through the first dischargeport (74) while on the other hand refrigerant compressed by the secondcompression mechanism (32) is discharged through the second dischargeport (75). The pressure of the refrigerant discharged through the firstdischarge port (74) is higher than the pressure of the refrigerantdischarged through the second discharge port (75). The refrigerantdischarged through the first discharge port (74) condenses in thecondenser (91). After leaving the condenser (91), the flow of thecondensed refrigerant is divided into two branch flows.

One of the two refrigerant branch flows is pressure-reduced by the firstexpansion valve (92), evaporates in the first evaporator (93), andmerges with the flow of the refrigerant discharged through the seconddischarge port (75). Thereafter, the merged refrigerant is drawn,through the first suction port (73), into the first compression chamber(71) of the first compression mechanism (31). Meanwhile, the otherrefrigerant branch flow, divided downstream of the condenser (91), ispressure-reduced by the second expansion valve (95), evaporates in thesecond evaporator (96), and is drawn, through the second suction port(76), into the second compression chamber (72) of the second compressionmechanism (32). At that time, in the refrigerant circuit (90), thedegree of opening of the second expansion valve (95) is set smaller thanthat of the first expansion valve (92), and the refrigerant evaporationpressure in the second evaporator (96) is set lower than that in thefirst evaporator (93). In addition, the refrigerant discharged throughthe second discharge port (75) is drawn, through the first suction port(73), into the first compression mechanism (31), in other words itundergoes two-stage compression.

In the refrigeration apparatus of the variation of the second embodimentprovided with the refrigerant circuit (90) having two refrigerantcirculating routes (plural refrigerant circulating routes) which differfrom each other in refrigerant evaporation temperature, the refrigerantcircuit (90) is activated by the single scroll compressor (10) havingthe two compression mechanisms (31, 32). And, since the firstcompression mechanism (31) and the second compression mechanism (32)differ in compression ratio and displacement volume, this makes itpossible to supply each refrigerant circulating route with refrigerantat a respective suitable pressure and at a respective suitablecirculation amount. As a result, it becomes possible for the apparatusto efficiently operate with smaller loss. In addition, since only thesingle scroll compressor (10) is provided, this accomplishesinstall-space savings and the apparatus cost is also cut down.

Additionally, for the case of the example of FIG. 7, when the differencebetween the first evaporation temperature and the second evaporationtemperature is substantial (for example, when the refrigerant circuit(90) is applied to a cold storage/frozen storage mode of operation or toan air-conditioning/frozen storage mode of operation), the requiredcompression ratio of the second compression mechanism (32) increases.Consequently, the amount of refrigerant leakage is liable to increase.In addition, the discharge temperature is liable to become excessivelyhigh. However, the variation of FIG. 8 employs two-stage compression, sothat the second compression mechanism (32) is no longer required tooperate at excessively great compression ratios. Consequently, theamount of refrigerant leakage is held low. Besides, an excessive rise intemperature is also suppressed by mixing of discharge gas from thesecond compression mechanism (32) and suction gas to the firstcompression mechanism (31). In addition, if the discharge temperature ofthe second compression mechanism (32) rises to excessive levels, thiscontributes to the degradation of refrigerant gas and lubrication oil.However, such a problem can be avoided.

On the other hand, the required compression ratio of the secondcompression mechanism (32) does not become too high, when the differencebetween the first evaporation temperature and the second evaporationtemperature is small. If two-stage compression is employed as shown inFIG. 8, the discharge loss becomes a problem. To cope with such a case,the configuration of FIG. 7 may be employed.

Therefore, the refrigerant circuit (90) may be configured, such that itbecomes switchable between the circuit of FIG. 7 and the circuit of FIG.8, as shown in FIG. 9. In this example, in the refrigerant circuit (90)of FIG. 8, a three-way switching valve (97) is disposed short of thejunction of a discharge pipe linked to the second discharge port (75)with a suction pipe extending between the first evaporator (93) and thefirst suction port (73). The three-way switching valve (97) is linked toa discharge pipe in connection with the first discharge port (74).

As a result of such arrangement, switching between the refrigerantcircuit (90) of FIG. 7 and the refrigerant circuit (90) of FIG. 8 ismade adequately for the operation of the apparatus. Operations accordingto the operational status of the refrigerant circuit are performed.

Third Embodiment of Invention

A third embodiment of the present invention is described. The scrollcompressor (10) of the third embodiment is an example which differs inconfiguration of the main mechanism (30) from the first and secondembodiments.

A main mechanism (30) of the third embodiment includes an orbitingscroll (50) of a so-called double-toothed type. As shown in FIG. 10, theorbiting scroll (50) has a single flat-plate part (55), a firstmovable-side wrap (53) formed in the lower surface of the flat-platepart (55), and a second movable-side wrap (54) formed in the uppersurface of the flat-plate part (55). A bearing part (64) is formed inthe lower surface of the flat-plate part (55) of the orbiting scroll(50). An eccentric part (21) of a drive shaft (20) is inserted into thebearing part (64).

A fixed scroll (40) includes a first stationary-side member (41) firmlyattached to a casing (11) at a position below the orbiting scroll (50),and a second stationary-side member (46) firmly attached to the uppersurface of the first stationary-side member (41). A firststationary-side wrap (42) with which the first movable-side wrap (53) isbrought into engagement is formed in the first stationary-side member(41). A second stationary-side wrap (47) with which the secondmovable-side wrap (54) is brought into engagement is formed in thesecond stationary-side member (46). The first stationary-side member(41) and the orbiting scroll (50) together form a first compressionchamber (71) of a first compression mechanism (31). The secondstationary-side member (46) and the orbiting scroll (50) together form asecond compression chamber (72) of a second compression mechanism (32).The first compression mechanism (31) and the second compressionmechanism (32) differ in compression ratio and displacement volume, asin the first and second embodiments.

Mounted between the second stationary-side member (46) and the orbitingscroll (50) is an Oldham ring (39) for preventing the orbiting scroll(50) from rotating. In addition, the first stationary-side member (41)has a main bearing (34) and the drive shaft (20) is rotatably supportedby the main bearing (34).

In the inside of the casing (11), a partition plate (85) is fixedlydisposed immediately above the main mechanism (30). An upper end (86) ofthe second stationary-side member (46) is inserted into the partitionplate (85). An O-ring (87) is mounted around the upper end (86) in thepartition plate (85). The O-ring (87) provides sealing between spacesdefined above and below the partition plate (85). In addition, an O-ring(88) is mounted around the outer peripheral surface of the secondstationary-side member (46). The O-ring (88) provides sealing betweenspaces defined above and below the second stationary-side member (46).

The casing (11) is provided with a first suction port (73) incommunication with the first compression chamber (71) through the firststationary-side member (41), and a second suction port (76) incommunication with the second compression chamber (72) through thesecond stationary-side member (46). Additionally, the casing (11) isprovided with a first discharge port (74) through which refrigerantflowing out to the space below the first stationary-side member (41)through the first compression chamber (71) and then through the firstdischarge opening (63) is discharged, and a second discharge port (75)through which refrigerant flowing out to the space above the partitionplate (85) through the second compression chamber (72) and then throughthe second discharge opening (66) is discharged.

Other configurations are almost the same as each of the above-describedembodiments, and their description is omitted accordingly. The samereference numerals as the first and second embodiments indicate the samestructural members as the first and second embodiments.

Although diagrammatical representation of a refrigerant circuitemploying the scroll compressor (10) of the present embodiment isomitted, it is applicable to the refrigerant circuit (90) with the twocondensers (91, 94) differing in refrigerant condensation temperature inthe first embodiment (FIG. 6) and to the refrigerant circuit (90) withthe two evaporators (93, 96) differing in refrigerant evaporationtemperature in the second embodiment (FIGS. 7 through 9).

And, also in the third embodiment, the refrigerant circuit (90) isactivated by the single scroll compressor (10) having the twocompression mechanisms (31, 32) in the refrigeration apparatus providedwith the refrigerant circuit (90) having two refrigerant circulatingroutes (plural refrigerant circulating routes) differing in refrigerantcondensation temperature and/or refrigerant evaporation temperature.And, since the first compression mechanism (31) and the secondcompression mechanism (32) differ in compression ratio and displacementvolume, this makes it possible to supply each refrigerant circulatingroute with refrigerant at a respective suitable pressure and at arespective suitable circulation amount. As a result, it becomes possiblefor the apparatus to efficiently operate with smaller loss. In addition,since only the single scroll compressor (10) is provided, thisaccomplishes install-space savings and the apparatus cost is also cutdown.

Furthermore, in accordance with the third embodiment, it employs theorbiting scroll (50) having the first movable-side wrap (53) formed in astanding manner on one surface of the flat-plate part (55) and thesecond movable-side wrap (54) formed in a standing manner on the othersurface of the flat-plate part (55). As a result of such arrangement,the number of component parts is reduced and the cost can be cut down.In addition, thrust loads act above and blow the flat-plate part (55) ofthe orbiting scroll (50), but they act in opposite directions.Therefore, in comparison with conventional scroll compressors having amovable wrap on only one side, thrust bearing loss is lessened and theefficiency is high.

In addition, even if the compression ratio of either one of the routesis high and as a result the temperature of discharge gas becomes high,heat generated in the upper and lower compression chambers (71, 72) istransferred through the flat-plate part (52) positioned therebetween.This lessens the rise in temperature. Therefore, improvements inapparatus reliability is accomplished.

Other Embodiments

The present invention may be configured as follows with respect to theabove-described embodiments.

For example, in each of the above-described embodiments, the descriptionhas been made in terms of a scroll compressor having two compressionmechanisms (31, 32) in the inside of the single casing. Alternatively,the present invention is applicable to displacement compressors otherthan the scroll compressors.

In addition, with respect to the configuration in which the twoscroll-type compression mechanism (31, 32) are provided in the inside ofthe single casing (11), each of the above-described embodiments are onlyexamples. Adequate modifications may be made.

Furthermore, the present invention is applicable to cases wherein, in arefrigerant circuit provided with three or more refrigerant circulatingroutes having their respective refrigerant condensation temperatures andrefrigerant condensation temperatures, two of the three or morerefrigerant circulating routes are activated. In addition, in theabove-described embodiments, the description has been made in terms ofan example in which the present invention is applied to a refrigerantcircuit provided with two refrigerant circulating routes having the samerefrigerant condensation or evaporation temperature. Alternatively, thepresent invention is applicable to a refrigerant circuit provided withtwo refrigerant circulating routes differing in refrigerant condensationtemperature as well as in refrigerant evaporation temperature (i.e., arefrigerant circuit in which the entrance and exit sides of the firstand second compression mechanisms (31, 32) have their respectivediffering pressures (temperatures)).

Additionally, the two compression mechanisms (31, 32) which are disposedwithin the single casing (11) do not necessarily have differentcompression ratios or different displacement volumes, and it may be sodesigned as to cope with the difference in refrigerant evaporationtemperature by control by means of an expansion valve or the like.

INDUSTRIAL APPLICABILITY

As has been described above, the present invention is usefullyapplicable to a refrigeration apparatus provided with a refrigerantcircuit having a plurality of refrigerant circulating routes and capableof operation in a mode where the refrigerant circulating routes differfrom each other in refrigerant evaporation temperature and/orrefrigerant condensation temperature.

1. A refrigeration apparatus provided with a refrigerant circuit havinga plurality of refrigerant circulating routes and capable of operationin a mode where the plurality of refrigerant circulating routes differin at least one of refrigerant evaporation temperature and refrigerantcondensation temperature, wherein a compressor of the refrigerantcircuit comprises a single casing in which a first compression mechanismlinked to a first refrigerant circulating route and a second compressionmechanism linked to a second refrigerant circulating route are arranged.2. The refrigeration apparatus of claim 1, wherein the first and secondcompression mechanisms differ from each other in compression ratio. 3.The refrigeration apparatus of claim 1, wherein the first and secondcompression mechanisms differ from each other in displacement volume. 4.The refrigeration apparatus of claim 1, wherein: the first and secondcompression mechanisms are scroll compression mechanisms, an orbitingscroll integrated by sequentially layering a first flat-plate part, afirst movable-side wrap, a second flat-plate part and a secondmovable-side wrap, and a fixed scroll having a first stationary-sidewrap which engages the first movable-side wrap and a secondstationary-side wrap which engages the second movable-side wrap areprovided, the first stationary-side wrap and the first movable-side wraptogether form the first compression mechanism, and the secondstationary-side wrap and the second movable-side wrap together form thesecond compression mechanism.
 5. The refrigeration apparatus of claim 1,wherein: the first and second compression mechanisms are scrollcompression mechanisms, an orbiting scroll having a first movable-sidewrap formed in standing manner on one surface of a flat-plate part and asecond movable-side wrap formed in standing manner on the other surfaceof the flat-plate part, and a fixed scroll having a firststationary-side wrap which engages the first movable-side wrap and asecond stationary-side wrap which engages the second movable-side wrapare provided, the first stationary-side wrap and the first movable-sidewrap together form the first compression mechanism, and the secondstationary-side wrap and the second movable-side wrap together form thesecond compression mechanism.
 6. The refrigeration apparatus of claim 1,wherein: the first and second compression mechanisms are scrollcompression mechanisms.
 7. The refrigeration apparatus of claim 1,wherein: the first and second compression mechanisms are displacementcompression mechanisms.